Subject: CVE-2024-49957: ocfs2: fix null-ptr-deref when journal load failed.

From: Greg Kroah-Hartman <[email-masked]>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

ocfs2: fix null-ptr-deref when journal load failed.

During the mounting process, if journal_reset() fails because of too short
journal, then lead to jbd2_journal_load() fails with NULL j_sb_buffer. 
Subsequently, ocfs2_journal_shutdown() calls
jbd2_journal_flush()->jbd2_cleanup_journal_tail()->
__jbd2_update_log_tail()->jbd2_journal_update_sb_log_tail()
->lock_buffer(journal->j_sb_buffer), resulting in a null-pointer
dereference error.

To resolve this issue, we should check the JBD2_LOADED flag to ensure the
journal was properly loaded.  Additionally, use journal instead of
osb->journal directly to simplify the code.

The Linux kernel CVE team has assigned CVE-2024-49957 to this issue.

Affected and fixed versions
===========================

	Issue introduced in 2.6.32 with commit f6f50e28f0cb and fixed in 5.10.227 with commit bf605ae98dab
	Issue introduced in 2.6.32 with commit f6f50e28f0cb and fixed in 5.15.168 with commit ff55291fb367
	Issue introduced in 2.6.32 with commit f6f50e28f0cb and fixed in 6.1.113 with commit 82dfdd1e31e7
	Issue introduced in 2.6.32 with commit f6f50e28f0cb and fixed in 6.6.55 with commit 86a89e75e9e4
	Issue introduced in 2.6.32 with commit f6f50e28f0cb and fixed in 6.10.14 with commit f60e94a83db7
	Issue introduced in 2.6.32 with commit f6f50e28f0cb and fixed in 6.11.3 with commit 387bf565cc03
	Issue introduced in 2.6.32 with commit f6f50e28f0cb and fixed in 6.12-rc1 with commit 5784d9fcfd43

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2024-49957
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	fs/ocfs2/journal.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/bf605ae98dab5c15c5b631d4d7f88898cb41b649
	https://git.kernel.org/stable/c/ff55291fb36779819211b596da703389135f5b05
	https://git.kernel.org/stable/c/82dfdd1e31e774578f76ce6dc90c834f96403a0f
	https://git.kernel.org/stable/c/86a89e75e9e4dfa768b97db466ad6bedf2e7ea5b
	https://git.kernel.org/stable/c/f60e94a83db799bde625ac8671a5b4a6354e7120
	https://git.kernel.org/stable/c/387bf565cc03e2e8c720b8b4798efea4aacb6962
	https://git.kernel.org/stable/c/5784d9fcfd43bd853654bb80c87ef293b9e8e80a